src/hooks.ts

@@ -99,7 +99,7 @@ function onLoad() {
     for (const lib of Zotero.Libraries.getAll()) {
       needFetchItems = needFetchItems.concat(
         (await Zotero.Items.getAll(lib.id)).filter((item: Zotero.Item) => {
-          return item.isRegularItem();
+          return item.isRegularItem() && !item.isCollection();
         }),
       );
     }

src/modules/tldrFetcher.ts

@@ -13,7 +13,7 @@ export class TLDRFetcher {
 
   constructor(item: Zotero.Item) {
     this.zoteroItem = item;
-    if (item.isRegularItem()) {
+    if (item.isRegularItem() && !item.isCollection()) {
       this.title = item.getField("title") as string;
       this.abstract = item.getField("abstractNote") as string;
     }